178 [August, 



13 (14). Frons narrow and extensively yellowish, ventral siu'face of male 



abdomen not very bristly, end of male front tarsi yellow... 



iiigrimana, Mg. 



14 (13). Frons wider and pale only in front, ventral surface of male abdomen 



very bristly, male front tarsi black varipes, Mg. 



The genus Madiza has been removed to near Desmometopa in the 

 Milicliidse. 



(To he continued). 



A EEVISION OF THE BRITISH SPECIES OF PTENIDIUM, Erichson 

 BY H. BRITTEN, F.E.S., AND E. A. NEWBERY. 



A revision of this genus lias admittedly been long needed. The 

 collections of the late Mr. Matthews were purchased by the Natural 

 History Museum, but with the exception of the types, the British 

 collection is now in tlio hands of Professor Ericson for examination, 

 and therefore not available at present. The state of the European 

 portion, in which as many as three or four species often stand under 

 one name, is a sufficient indication of the uselessness of his tables and 

 descriptions, even to Matthews himself, nor have we found other 

 British collections that we have examined more correctly named. 



It is to Herr K. Flach's " Bestimmungstabelle " (Verh. z.-b. 

 Ges. Wien, xxxix, 1889) that we are indebted for the most valuable 

 characters in the following table. These are taken chiefly from the 

 scutellum, which has a transverse basal furrow bearing normally 

 a short central keel and two or more punctures ; the shape and 

 furrowing of the prosternal Iceel ; and the punctuation and pubescence 

 of the upper surface, which latter is extremely short in P. gressneri 

 and Isevigatum, very long and conspicuous in pnnctatum, fnscicorne, 

 hrisontl,2)usillm)i, Sbjid 7iitich(m, a,m\ intermediate in the other species. 

 Of course this can only be useful in fresh specimens. Tlie thorax has 

 normally four round, foveiform pmictures placed transversely at the 

 base, the size and depth of whicli are variable, and of little use for 

 the separation of species. Nearly all of them have the elytra paler at 

 the apex. A good half-inch objective is recommended for the examina- 

 tion of most of the ab6ve-mentioned characters, and examples can 

 usually be named fi-om the upper-side alone, but in doubtful cases 

 recourse must be had to the form of the prosternal keel. 



